JPH04112005A - Ceramic heat radiating baseplate and production thereof - Google Patents

Abstract

PURPOSE:To enhance the heat radiation effect of the electronic parts by laminating a dense ceramic layer on a porous ceramic layer and integrally sintering them and forming the opened pores in the porous ceramic layer and forming the porous ceramic layer into the passage of a refrigerant and impregnating the opened pores with molten copper-based alloy and coagulating it. CONSTITUTION:A ceramic heat radiating baseplate 10 is obtained by laminating a dense ceramic layer 10b on both sides of a porous ceramic layer 102 and integrally sintering them. Metallic pipes 11, 12 are constituted of the metallic material whose thermal expansion coefficient is nearly equal to a ceramic baseplate 10 made of alumina. The metallic pipes are brazed by a hard solder 16 and integrated with the baseplate 10. A through-hole 17 is bored through the dense ceramic layer 10b of the lowermost layer of the baseplate 10. A gaseous refrigerant e.g. gaseous freon 13 is blown thereinto from both of the metallic pipes 11, 12 and discharged from the through-hole 17 through the porous ceramic layer 10a. Heat release of the electron parts 14, 15 is removed which are placed on the dense ceramic layer 10b of the uppermost layer. Since copper- based alloy is coagulated in the opened pores of the porous ceramic layer 10a, heat generated from the electron parts 14, 15 is rapidly cooled by the gaseous refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor substrate material containing alumina as a main component and manufactured by a green/-1 multilayer lamination method. More specifically, the present invention relates to a ceramic heat dissipation board for dissipating heat generated by electronic components and a method of manufacturing the same.

[Prior Art] Conventionally, this type of ceramic heat dissipation board has been manufactured by attaching Cu metal or Cu-W sintered alloy with high thermal conductivity to heat sink metal by metallization or brazing in order to improve heat dissipation. It was bonded to the surface of the ceramic substrate in a solid state.

[Problem to be solved by the invention] However, in order to avoid a decrease in strength due to distortion during bonding, the heat sink metal must be selected from those whose coefficient of thermal expansion matches that of the ceramic substrate. , when an alumina substrate is used as the ceramic substrate, the heat sink metal is Cu-W, Cu-Mo,
Only sintered alloys with a low coefficient of thermal expansion, such as W-Ag, could be used, and there was a certain limit to the heat dissipation effect.

An object of the present invention is to provide a ceramic heat dissipation board that can be bonded with various heat sink metals with high strength and that can increase the heat transfer area by increasing the bonding interface between the ceramic substrate and the metal, and a method for manufacturing the same. .

Another object of the present invention is to provide a ceramic heat dissipation board that has a high heat dissipation effect for electronic components and allows electronic components to be mounted at high density, and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve the above object, the ceramic heat dissipation substrate of the present invention includes a porous ceramic layer and a dense ceramic layer laminated on both or one side of the porous ceramic layer and integrally sintered. A laminated sintered body in which open pores are formed in a porous ceramic layer is used as a support, and the porous ceramic layer is used as a coolant passage, and a molten copper alloy is impregnated and solidified into the open pores. Features.

In addition, in the method for manufacturing a ceramic heat dissipation board of the present invention, first, a first sintering aid and a first water-soluble binder are added and mixed to a first alumina sol using water as a dispersion medium to prepare a slurry for a dense layer. The slurry for dense layer is formed into a film and dried to form a green sheet for dense layer. Next, no sintering aid is added to the second alumina sol using water as a dispersion medium, or a second sintering aid and a second water-soluble binder are added and mixed in a smaller amount than the first sintering aid to form a porous layer. A green sheet for the porous layer is formed by preparing a slurry for the porous layer and drying the slurry for the porous layer. Next, the dense layer green sheet is adhered to both sides or one side of the porous layer green sheet, and the adhered green sheet is
A laminated sintered body is formed by firing at 0 to 1600°C. Furthermore, the porous ceramic layer of the laminated sintered body is impregnated with the molten copper alloy and solidified.

The ceramic raw materials constituting the porous ceramic layer and the dense ceramic layer of the present invention both have an alumina content of 9.
It is alumina with a high purity of 0 to 999%. Both the slurry for the dense layer and the slurry for the porous layer mainly contain alumina sol using water as a dispersion medium. The alumina sol is an alumina colloid liquid obtained by hydrolyzing aluminum alkoxide and peptizing the respective hydrolysis products, and is preferably an alumina sol of fine colloidal particles prepared by a so-called sol-gel method.

The difference between the preparation methods of the slurry for the dense layer and the slurry for the porous layer is that the former uses a sintering aid or 100% by weight alumina sol.
The latter contains no sintering aid or only a smaller amount of sintering aid than the former to increase the porosity of the ceramic layer. It's there. Examples of sintering aids for alumina include silicon dioxide, magnesium oxide, calcium oxide, magnesium acetate, and titanium dioxide. In the addition system of magnesium oxide and silicon dioxide, it is preferable to add at least 0.1% by weight of calcium oxide.

The water-soluble binder is added in an amount of 10 to 80% by weight based on the solid content of the alumina sol in both the dense layer slurry and the porous layer slurry. This binder tends to create pores in the ceramic layer when the binder is removed during sintering.
When reducing the porosity, a small amount within the above range is added to the alumina sol. Examples of water-soluble binders include polyvinyl alcohol and water-soluble acrylic. The binder contained in the slurry for the dense layer may be different from the binder contained in the slurry for the porous layer.

Methods for forming slurries for dense layers and porous layers include the doctor blade method, extrusion molding method, roll rolling method, slurry casting method, etc. A good doctor blade method is preferred. When forming a slurry for a porous layer, ammonia or an alkaline substance such as amines may be added to the slurry to form a gel in the slurry, thereby increasing the porosity.

After forming the slurry for the dense layer and the slurry for the porous layer, they are dried at 30 to 95°C, respectively, to form a green sheet for the dense layer and a green sheet for the porous layer. The green sheet for the dense layer, which is the lowest layer, may be provided with holes through which the coolant passes.

Next, an adhesive is applied to both sides or one side of the green sheet for the porous layer, and the adhesive is applied at a temperature of 0 to 70°C at a rate of 5 to 200 kg/c.
The dense layer green sheet is adhered to the porous layer green sheet and laminated with a pressure of m'.

As this adhesive, an aqueous adhesive such as a cellulose derivative, an acrylic emulsion, or a vinyl acetate emulsion, or a non-aqueous adhesive such as an acrylic resin, a butyral resin, or a vinyl resin can be used.

In addition to the three layers in which dense layer green sheets are stacked on both sides of a porous layer green sheet, dense layers and porous layers may be stacked alternately depending on the purpose of the ceramic substrate. It is also possible to have multiple layers combined.

After the green sheets are laminated, they are cut into predetermined dimensions, placed in a firing furnace, and fired. Firing is performed at a temperature range of 1200 to 1600° C. for 1 to 2 hours under atmospheric pressure in order to obtain the desired porosity. The higher the firing temperature and the longer the firing time, the lower the porosity. If the temperature is less than 1200°C, the porosity of the dense ceramic layer increases, and the temperature is lower than 160°C.
If the temperature exceeds 0°C, the porosity of the porous ceramic layer decreases and the object of the present invention cannot be achieved.

In the ceramic heat dissipating substrate of the present invention, the porosity of the porous ceramic layer is 20 to 20 depending on the amount of sintering aid added or the firing temperature.
60%, and the porosity of the dense ceramic layer is 0.
．． It is controlled within the range of 0.01 to 5%.

Open pores are formed in the porous ceramic layer of the laminated sintered body obtained by the above firing. Here, open pores are different from closed pores and refer to fine pores that are continuous from one end of the sintered body to the other and allow fluid to pass through.

After the porous ceramic layer of this laminated sintered body is impregnated with a molten copper alloy, it is cooled and solidified.

It is desirable that the melting point of this laminated sintered body is at least higher than the melting point of the copper alloy. In order to prevent oxidation, it is preferable to carry out the impregnation in a vacuum. This impregnation treatment may be performed multiple times if necessary.

As the copper alloy of the present invention, it is preferable to use a Cu-Ni precipitation hardening copper alloy or a Cu-AM martensitic transformation hardening copper alloy.

This is because when the above-mentioned alloy is used as a copper-based alloy, the interfacial stress generated due to the difference in thermal expansion when bonded to a sintered body is alleviated by precipitation aging or martensitic transformation of precipitates.

By mounting electronic components such as capacitors and resistor chips on the dense ceramic layer on the top layer of the ceramic heat dissipation board, which is a laminated sintered body, and passing a coolant through the porous ceramic layer,
Heat generated by electronic components can be dissipated.

As shown in FIGS. 1 to 4, metal tubes 11 and 12 are connected to both the front and rear ends of the ceramic heat dissipating substrate 1o, and the coolant 13 is passed through the porous ceramic layer 10a of the substrate 1o to form the outermost layer. A method for removing heat generated by electronic components 14 and 15 mounted on a dense ceramic layer 10b, and a method for removing heat generated from electronic components 14 and 15 mounted on a dense ceramic layer 10b.As shown in FIGS. After drilling a through hole 27 with a diameter of approximately 4 to 6 mm, the metal tubes 21 and 2 are inserted into the through hole 27.
2 perpendicularly to the layer 20b, and the coolant 23 is passed through the porous ceramic layer 20a of the substrate 20 to remove the heat generated by the electronic components 24 and 25 mounted on the uppermost dense ceramic layer 20b.

These metal tubes 11, 12, 21, and 22 are made of a metal material, such as a Kovar alloy, whose thermal expansion coefficient is approximately the same as that of the alumina ceramic substrate.

These metal tubes are brazed with a hard solder 16, such as silver solder, brass solder, copper solder, etc., and integrated with the substrate 10 or 20. The three-layer laminated ceramic heat dissipation board 10 shown in FIGS. 1 and 2 is inserted into the metal tubes 11 and 12, and the five-layer laminated ceramic heat dissipation board 10 shown in FIGS. Glued to the end face. A through hole 17 having a diameter of 60 to 900 .mu.m is formed in the lowermost dense ceramic layer 10b of the substrate 1O in FIGS. 1 and 2, depending on the thickness of this layer 10b. The through holes 17 and the aforementioned through holes 27 are formed in the green sheet before firing.

Further, a sealing layer 10c or 20c is formed on both sides of the ceramic heat dissipation board 10 to which the metal tubes 11 and 12 are not connected, and on the circumferential side of the ceramic heat dissipation board 20 to prevent the coolant 13 or 23 from leaking, respectively. This sealing is performed by coating the stacked green sheets with a slurry for a dense layer and firing.

The substrate 10 in FIGS. 1 and 2 includes metal tubes 11 and 12.
A refrigerant gas, for example, Freon gas, is blown in from both sides and discharged from the through hole 17 through the porous ceramic layer 10a.

A refrigerant gas or cooling water is introduced into the substrate 10 of FIGS. 3 and 4 through a metal tube 11, and is discharged from a metal tube 12 through a porous ceramic layer 10a.

A refrigerant gas or cooling water is introduced into the substrate 20 of FIGS. 5 and 6 from a metal tube 21 and is discharged from a metal tube 22 through a porous ceramic layer 20a.

Since the copper-based alloy solidifies in the open pores of the porous ceramic layer 10a or 20a, electronic components 14, 15 or 24.
The heat generated from 25 is quickly cooled down by refrigerant gas or cooling water.

[Effects of the Invention] As described above, the ceramic heat dissipation substrate of the present invention has a dense ceramic layer laminated on both or one side of a porous ceramic layer and is integrally sintered, and the porous ceramic layer is heated. Because it is formed by impregnating and solidifying a copper-based alloy with high conductivity, it can be bonded with a variety of heat sink metals with high strength, and it can also increase the heat transfer area by increasing the bonding interface between the ceramic substrate and metal. . As a result, the heat dissipation effect of the electronic components is high, and the electronic components can be mounted with high density.

In particular, we use precipitation-hardening copper-based alloys or martensitic transformation-hardening copper-based alloys as heat sinks, in which the interfacial stress generated by thermal expansion differences when bonded to a porous ceramic layer is alleviated by precipitation aging or martensitic transformation of precipitates. If used as a metal material, a high-strength ceramic substrate can be obtained.

[Example] Next, embodiments of the present invention will be described in detail based on the drawings.

<Example 1> Aluminum isopropoxide [AQ (C3H,O)
3] was hydrolyzed to produce boehmite [A Q OOH], which was peptized by adding water adjusted to pH 2 to 4 to obtain a stable pseudo-boehmite sol with an alumina concentration of 5% by weight.

In order to prepare a slurry for a dense layer, colloidal silica, magnesium acetate, and calcium acetate were added as sintering aids, and polyvinyl alcohol was added as a water-soluble binder to the slurry. When these sintering aids are sintered into a dense ceramic layer, the composition ratio is AQ, O,: 5if2: MgO: Ca0 = 92:
They were added at a ratio of 7:2:1. The binder was added in an amount of 40% by weight based on the solid content. As a result, a slurry having a solid content of 10% by weight was prepared.

This slurry was coated on a high-density polyethylene tape as a moving carrier to a thickness of 1.2 mm using a doctor blade method, and then dried to remove water, which is the dispersion medium of the slurry, to a thickness of approximately 60 μm. A green sheet for dense layer was obtained.

On the other hand, a green sheet for a porous layer having a thickness of about 60 μm was obtained in the same manner as above except that no sintering aid was added to facilitate porosity. Nine through holes with a diameter of 100 μm were bored per 1 square cm in the green sheet for the dense layer, which was the lowest layer. Next, an isopropyl alcohol solution of polyvinyl butyral with a concentration of 1% is applied as an adhesive to both sides of the green sheet for the porous layer, and the green sheet for the dense layer is superimposed on both sides of this sheet and adhered to form three layers. A laminated green molded body having a thickness of about 180 μm was obtained. After cutting this green molded body into a square of 80 x 80 mm,
A slurry for a dense layer was coated on both sides to cover a green molded body for a porous layer.

Next, this green molded body was placed in a firing furnace and heated to 1500°C.
A three-layer alumina substrate was obtained by firing under atmospheric pressure for 1 hour. The dense alumina layer and porous alumina layer of this three-layer alumina substrate have an alumina content of 92% and 99%, respectively.
It was a 5% alumina sintered body layer. Open pores were formed in the porous alumina layer.

Furthermore, this three-layer alumina substrate was placed in a vacuum high-temperature furnace heated to 900°C, and after evacuating, precipitation hardening type Cu-N1- was melted into the porous alumina layer of this three-layer alumina substrate.
Impregnated with AQ gold alloy. The three-layer alumina substrate impregnated with the copper-based alloy was taken out of the furnace and allowed to cool to room temperature.

Copper-based alloy was solidified in the open pores of the porous layer of this three-layer alumina substrate. Also, the bending strength of this board is 50 kg.
f/mm”.

As shown in FIGS. 1 and 2, both front and rear ends of the laminated and sintered ceramic heat dissipation substrate 10 with a thickness of 100 μm are coated with Kovar alloy (Fe).
40%, Ni 40%, Co 20%) metal tube 11
and 12 and brazed with silver solder 16, Freon gas was blown into both the metal tubes 11 and 12 and discharged from the through hole 17 through the porous ceramic layer 10a. 10b showed an extremely high heat dissipation effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the ceramic heat dissipation board of the present invention. FIG. 2 is a perspective view thereof. FIG. 3 is a sectional view of another ceramic heat dissipation board of the present invention. FIG. 4 is a perspective view thereof. FIG. 5 is a sectional view of yet another ceramic heat dissipation board of the present invention. FIG. 6 is a perspective view thereof. 10.20: Ceramic heat sink, 10a, 20a: Porous ceramic layer, 10b, 20b
:Dense ceramic layer, 13.23: Refrigerant. 0a 0b Figure Figure

Claims (1)

[Claims] 1) Supporting a laminated sintered body in which a dense ceramic layer is laminated on both or one side of a porous ceramic layer and sintered integrally, and open pores are formed in the porous ceramic layer. 1. A ceramic heat dissipation board having a porous ceramic layer as a body and a fluid passageway, the ceramic heat dissipation board characterized in that a molten copper alloy is impregnated into the open pores and solidified. 2) The ceramic heat dissipation board according to claim 1, wherein the copper-based alloy is a precipitation-hardening copper-based alloy or a martensitic transformation-hardening copper-based alloy. 3) The ceramic heat dissipation board according to claim 1 or 2, wherein the dense ceramic layer is provided with through holes communicating with the open pores of the porous ceramic layer. 4) Prepare a slurry for a dense layer by adding and mixing a first sintering aid and a first water-soluble binder to a first alumina sol using water as a dispersion medium, and drying this slurry for a dense layer to form a film. A green sheet for a dense layer is formed, and a sintering aid is not added to the second alumina sol using water as a dispersion medium, or a second sintering aid is added in a smaller amount than the first sintering aid and a second water-soluble A slurry for a porous layer is prepared by adding and mixing a binder, a green sheet for a porous layer is formed by forming and drying this slurry for a porous layer, and the above-mentioned is applied to both or one side of the green sheet for a porous layer. Dense layer green sheets are bonded with an adhesive, the bonded green sheets are fired at 1200 to 1600°C to form a laminated sintered body, and the molten copper-based alloy is bonded to the porous ceramic of the laminated sintered body. A method of manufacturing a ceramic heat dissipation substrate by impregnating and solidifying a layer. 5) Production of a ceramic heat dissipation substrate according to claim 4, wherein either or both of the first and second alumina sol is an alumina colloid liquid obtained by hydrolyzing aluminum alkoxide and then peptizing the hydrolyzed product. Method.